BoilerFaultCodesYour boiler has detected a faulty internal temperature sensor, which means it cannot accurately measure how hot the water is and has stopped running for safety.
Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.
Technical description: CH flow NTC sensor defective.
What causes this fault?
This fault occurs when the sensor responsible for monitoring the temperature of the water leaving your boiler fails or sends an incorrect signal. The most common reason is the electrical component inside the sensor wearing out over time, though it can also be caused by corroded wiring connections or a build-up of heat that has damaged the sensor’s sensitivity.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like E2 — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.
Worcester Bosch Greenstar 30HE is discontinued — time for a new one?
Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.
Affiliate links — we may earn a commission at no extra cost to you.